algorithmic-trading-anthology-july-2026-la-nina-rainfall-in-australian-agribusiness

Conclusion: Null

No effect at any horizon tested, across 24 tests.

Every test, against the significance threshold

persistence-robust p · left is stronger evidence

Filled markers fall below the 0.05 threshold before multiple-testing correction; hollow markers do not. Correction is applied across the whole batch, so an individual marker clearing the line is not a result on its own.

Tests

ticker × horizon

p < 0.05

uncorrected

Best q

0.95

BH-FDR

Survived

q ≤ 0.10

Method

Hypothesis

La Niña delivers above-average rain to the eastern cropping belt. Volume-levered handlers and input suppliers earn on tonnes, not price.

Rule

signal = soi_3m # 3-month mean SOI

prior = +1 # higher SOI -> higher returns

function test(instrument, horizon h):

y = sum(returns[instrument], t+1 .. t+h) # strictly forward

x = signal[t] # known at t

beta, t_stat = OLS(y ~ x) with Newey-West HAC, lag = h + 1

# null: slide x against y by every admissible offset, so

# persistence appears identically under the null

null = [slope(y, roll(x, k)) for k in all offsets]

p = (count(abs(null) >= abs(beta)) + 1) / (len(null) + 1)

return beta, t_stat, p

reject if Benjamini-Hochberg q <= 0.10 across the whole study

Evaluation

Table 1 · Every test in this hypothesis

forward return regressed on the SOI signal

Instrument	Horizon	n	β	HAC t	Shift p	Sign as predicted
GNC.AX	1m	338	+0.0008	+1.59	0.076	yes
GNC.AX	3m	336	+0.0015	+1.26	0.112	yes
GNC.AX	6m	333	+0.0026	+1.25	0.141	yes
GNC.AX	12m	327	+0.0063	+1.74	0.058	yes
ELD.AX	1m	402	-0.0010	-1.50	0.868	no
ELD.AX	3m	400	-0.0025	-1.30	0.818	no
ELD.AX	6m	397	-0.0048	-1.38	0.813	no
ELD.AX	12m	391	-0.0151	-2.30	0.975	no
NUF.AX	1m	400	+0.0001	+0.23	0.436	yes
NUF.AX	3m	398	-0.0004	-0.37	0.604	no
NUF.AX	6m	395	-0.0020	-0.84	0.697	no
NUF.AX	12m	389	-0.0038	-1.02	0.704	no
DNL.AX	1m	274	+0.0004	+0.69	0.309	yes
DNL.AX	3m	272	+0.0012	+0.70	0.292	yes
DNL.AX	6m	269	+0.0008	+0.24	0.429	yes
DNL.AX	12m	263	-0.0032	-0.55	0.620	no
AAC.AX	1m	297	-0.0011	-2.21	0.986	no
AAC.AX	3m	295	-0.0033	-2.88	0.996	no
AAC.AX	6m	292	-0.0058	-2.82	0.982	no
AAC.AX	12m	286	-0.0096	-2.85	0.988	no
RIC.AX	1m	402	+0.0000	+0.07	0.458	yes
RIC.AX	3m	400	+0.0003	+0.37	0.370	yes
RIC.AX	6m	397	+0.0010	+0.64	0.277	yes
RIC.AX	12m	391	+0.0050	+1.47	0.056	yes

+ 20 more rows− fewer rows

Shift p is the persistence-robust p-value and is the one that decides. HAC t is shown to demonstrate how far conventional inference overstates the evidence.

Reference

Instruments

last price and one-month change, live from Yahoo Finance

Symbol	Notes
AAC.AX	Australian Agricultural Company — listed on ASX, in AUD.
DNL.AX	Dyno Nobel — listed on ASX, in AUD.
ELD.AX	Elders — listed on ASX, in AUD.
GNC.AX	GrainCorp — listed on ASX, in AUD.
NUF.AX	Nufarm — listed on ASX, in AUD.
RIC.AX	Ridley Corporation — listed on ASX, in AUD.

Sample

1970–2026 monthly

Sources

Queensland Department of Agriculture and Fisheries. Southern Oscillation Index. The Long Paddock. Monthly, 1876–. www.longpaddock.qld.gov.au/soi/soi-data-files

Yahoo Finance. Historical market prices. Adjusted close, month-end. Retrieved with yfinance. finance.yahoo.com

Revision history

Rev	Stage	Status	Change
01	Draft	—	Direction and criteria fixed before the experiment ran
02	Tested	Null	24 tests; 0 below p=0.05, none surviving FDR